Four Paws and a Tale
by Garrae
Summary: Going to university was supposed to broaden Kate Beckett's mind. Broadening her genetic make-up was going just a little too far. By popular request, how Beckett became a shapeshifter and what happened thereafter. Rating warning for the final chapter, which is mildly M. Caskett Cats Universe #2.
1. Chapter 1

**Chapter 1: Dream a little dream**

 _ **Hallowe'en, 1999**_

 _Uh, what just happened?_

Kate Beckett looks up at the full moon over Palo Alto and rubs her throat. She didn't think she'd had _that_ much to drink, but she must have had plenty. That had been one hell of a bad dream, and _how_ is she lying outside in a park?

She struggles to her feet, and tries to remember the evening so far. Sasha, formally Alexander but Sasha is so much sexier, and she had been dancing around each other in their Russian class since the moment she'd hit Stanford. He was a totally cute guy, so she'd been really pleased when they started dating, and, well, they'd really lit each other up: wow! He was seriously hot and _very_ talented. Her Russian had improved enormously, too. So they had agreed they'd meet at Lita's Hallowe'en party – oh God, the party, surely someone's missed her, oh God. She fumbles for her phone and calls Lita.

"Hey, it's Kate."

"Kate, you skipped on me. Where'd you go?"

"Out for a walk," she lies. "Ghost hunting with Sasha, 'cause it's Hallowe'en. I'll be back in a bit. Just cooling off, you know?"

"You take care now," Lita's Alabama drawl comes through the connection. "We got some partying still to do."

"Back soon. Later."

"Later."

Okay, so cute, hot Sasha had been there, a bit later than she'd hoped but it's okay, and they'd been doing vodka shots, but she'd only had three and her tolerance is a lot higher than that, so… oh God, he must have spiked them, _shit_. She looks frantically down her front, but nothing's been displaced, and she doesn't have that post-sex feeling. Okay, not quite _oh shit_. But she vaguely remembers stumbling out here with him – oh, yeah, he'd driven. Hell, she'll need to find a cab. She pats her pockets. Okay, wallet still there, and when she checks, intact. This is all very weird.

She hunts through her jumbled memories again. Nothing's clear. But she'd swear that cute Sasha had turned into a big cat in the middle of a very heavy petting session, just when she'd been limp and satisfied for the first time, and bitten her neck clean through. It had hurt, too. She looks about. No blood on her; no blood on the grass. She pops her purse open for a small mirror in her powder compact and, in the bright light of the full moon, examines her neck. Nothing. Not a single mark. Not even a hickey, which is rather disappointing when she thinks about it. Usually the problem is _stopping_ getting hickeys.

Sasha is nowhere to be seen. This is annoying – no, infuriating. It's pretty crap for him to bring her out here – wherever _here_ is – and abandon her. Then again, it's truly _shit_ behaviour to spike her drinks. When she sees him again she's going to practice her Russian colloquialisms on him at some length. Then she's going to practice her self-defence moves. Stupid _asshole_ teen guy.

Stupid teen girl Kate, she thinks. Nothing _seems_ to have happened, if you discount the fact that she needs to find a street sign and a cab, but that's just dumb luck. She lurches round the corner, finds a sign, thinks rather fuzzily for a few moments, and then staggers towards some brighter lights to get a cab. Her hangover is already biting. She texts Lita that she's going back to the dorm, and collapses into her bed on the back of two Advil and a gallon of water. That sonofabitch Sasha is right off her Christmas card list.

She never sees him again. He's not at Russian class, or any other class, and when she asks about him Student Services can't help. It's as if he never enrolled at all. In fact, it's as if he'd never existed at all, which is very, very strange.

She stops worrying about it, or Sasha, quite soon, because after Christmas, of course, she has to go home for the funeral; and, only one semester later, to transfer to NYU. She still dreams about that Hallowe'en night, and of a big black cat under a bright full moon, slicing through her jugular vein: wakes, breathless and terrified, touching her neck. It's very weird, but it's just a nightmare, and she has more to worry about than nightmares.

Her father is a complaisant drunk, but he's a drunk. Most of the time he stumbles out and staggers home: all her months of trying to make him stop haven't worked, so now she's thinking of finding somewhere of her own. She's got plenty of money. Her mother had left her everything… including a very substantial insurance policy. Of course, that's because it had been set up as if both of her parents had died together, and her mother had never changed it as Kate had grown up. Still, she could find a new home, and she's pretty tempted already. In fact, she might just do that.

She's got classes the next day, but in the early evening she finds a real estate agent and picks up a ton of leaflets: repeats for a week until she's found a few she'd like to look at. One is just perfect. A couple of weeks later, she's in. Her father doesn't even notice. Kate tries not to care.

The one small disadvantage of her new apartment is that the area is a little – well, _lively_ , at night. She'd known that, but the multiple advantages of its size and duplex layout ( _two_ bedrooms, _wow_!) had easily outweighed that.

She discovers that the lively area might not be a _small_ disadvantage several months later, on an evening on which she'd been studying far too late in the NYU library, and, having not thought about her route home further than the subway, found herself right in the middle of a group of extremely drunken frat boys. Drunk would have been bad enough, but drunk and horny was a lot worse.

It starts to get scary when they don't move to let her out of the circle.

"Ooohh, we found a pretty one," one meathead starts.

"Excuse me, please," she asks. No-one shifts. In fact, they close in a little, effectively blocking her from anyone's sight.

"Hey, girl, wanna come have some fun?" The accompanying gesture hadn't left much to the imagination.

"No," she says. They still don't let her out.

"You look like you're up for it." She's not. She's really, really not. This is not going well at all, and she doesn't know what to do. Self-defence moves aren't going to help against this many men.

"Let me go," she says, a note of terror inflecting her voice.

"Naw. Come'n play with us. We'll show you a really good time."

The closing circle of several college seniors, all big – she suspects that they're a component of the football squad – is now really frightening. Hands reaching for her, bulky bodies pressing round her, the odour of stale alcohol and a hint of pot, everything coming in and in and they're starting to touch and grab and _oh Christ_ she's struggling and it's not working and she has to get out of here somehow and –

"Where'd she go?"

"What the fuck, man? You let her go?"

"I never. She just disappeared."

"You drunken asshat. We could really have got it on."

But… but she's right here. Well, she'd managed to wriggle out of the press of frightening bodies. She looks round. Hold on. Why's everything so much taller? Why's it all in black and white? Oh. Not black and white. Just… washed out. She takes a step, confused, and looks down –

What the actual _fuck_? That's not her foot. That's… that's… _it's a paw_! She sits back down, very quickly. Then she looks again. It's a paw. Well, two paws. She wiggles them. They seem to be attached to her. No. This is not real. She wasn't drinking. She certainly wasn't smoking strange herbs. She hasn't eaten any peculiar mushrooms lately. She must be dreaming. She is absolutely definitely not a cat. She is Kate Beckett and she is (one) human and (two) does _not_ believe in shapeshifting.

Shapeshifting involves pain, and stretching bones, and relocation of many muscles, and horrible gloopy stuff, and probably screaming, and especially torn clothes. None of this has occurred. Therefore she can't be shapeshifting. And anyway, she'd be a wolf. Not a plain ordinary _cat_.

She stretches out, and something catches the corner of her eye. This is one _hell_ of a dream, because she'd swear that was a tail. And those look suspiciously like claws. Well, even if it's a dream, she doesn't want trodden on. She pads over to a close-by, dark alley, and wonders rather bitterly why her dream didn't turn her into a big cat, rather than an ordinary one. Humph. The dream would be much better if she was a tiger. Or a lion. Or a wolf, even if that's canine. She wants to be a _predator_ , not a pet _._

Right now, she wants to predate (is that even a word?) those frat sonsabitches. See how they like being frightened for their lives.

That's odd. She's taller. Not her proper height, but taller. And there's a wino slumped in the corner who's staring at her in horror and shocked-cold sobriety… that's not a good bit of dream, because she can smell him and he _stinks_. He's also running – well, stumbling – for the alley exit. At least he's taken his stench with him. Ugh. She rubs at her nose, and realises that she still has – oh my Lord. Those are _huge_ paws, and when she flexes them, they have _huge_ claws. That's better. She likes this sort of a dream _much_ better.

Still, even if it's a dream, she'd like to go home. She stalks out on to the street, which is really rather quiet, then thinks that even in a dream scaring people isn't what her mother would have approved of. She shakes her head, retreating into the alley again before anyone can spot her. How can she be worrying about what her mother would have thought in a _dream_? She thinks she'd like to be herself again. Dreamtime is over.

Suddenly she's back to normal: Converses, jeans, cotton shirt, leather jacket, wool scarf. She slides out into the lights of the street, and goes home, collapsing on to her couch. She wakes up some time later, very confused by the dream, and even more confused by how dirty her hands are.

About the point she gratefully descends into a hot bath (another major advantage of this apartment), she realises that her _feet_ are dirty. Filthy, in fact. This is not so much strange as unbelievable. She washes them clean, hops out her bath and dries herself, tells herself she's an idiot – and thinks about becoming a cat.

Of course that isn't going to happen.

Oh. My. God. Oh _fuck_. Oh. My. God.

Staring back at her from her full-length mirror is a pure black, green-eyed, domestic cat. A very slim, very elegant, probably-Siamese cat. She stares at herself. She has _paws_. Four paws. She picks each paw up, and puts it down again, and flexes them. Four sets of claws run out. They're very neat. Her nail polish is missing, though. She turns around, and twists her head – some very elegant ears there, and even with yoga she couldn't bend like _this_ , wow! – and there, behind her, is a _tail_. She waves it, to check. Yep, hers.

About that point reality crashes over her head and she starts to scream. It emerges as a yowl. She closes her mouth, quickly, and curls up into a ball. This _is not real_. She doesn't _believe_ in the supernatural. She can't be a cat. It's not _possible_. She caterwauls again.

But… in her dream – oh shit, _was_ that a dream? – she wasn't just a cat. She thinks very hard about being larger – and suddenly there's a – um, what _is_ it? She hadn't taken any animal-related classes in Stanford, and certainly not at NYU – um, jaguar? Panther? Whatever it is, she _likes_ this one. Oh yes. Oooohhhhhh. That'll scare the _shit_ out of predatory rapist-frat boys. Oh, _hell_ , yes. She flexes one large paw and examines the claws with considerable pleasure, and then yawns at the mirror and enjoys the sight of some very sharp and gleaming teeth.

Well, now. This might not be so bad after all. Or, of course, she might have fallen asleep in the bath, and this is just another very, _very_ weird dream. She imagines herself human, and promptly is so, and even more promptly goes to bed, and sleeps.

Of course, it's not that simple, she realises when she wakes up, and tests to see if it's all still true. This time, she is quite definitely awake (she pinched herself, to check), and when she imagined herself a cat – she _was_. And then she was the big cat. (She really must look that up. Accuracy is important.)

And now she doesn't have the faintest idea what to do with her life. Shapeshifters are _not a thing_.

Correction. Shapeshifters _weren't_ a thing. Clearly, shapeshifters _are_ a thing, because she _is_ one.

That _sonofabitch_ Sasha!

Okay. No point crying over spilt milk. (Would her cat form lap it up, instead, she wonders? Do cats even cry?) She needs to get this sorted, and the _first_ thing she needs to do is make damn sure it's under her control. This is not something where random happenings will be helpful, and she has no desire to be an experimental lab subject. In addition, her police academy application is now less than a year away – graduation is less than a year away – and since this _change_? disaster? impossibility? was triggered by stress and terror, which is probably a pretty good composite definition of the Academy and certainly being a rookie Officer Beckett (please let her get to be an Officer Beckett), she'd better get this managed.

Control. Yes. She's good at that. Now. Since her mother, and her father… and everything.

And so she practices. She becomes extremely good at spotting small dark corners, and small dark alleyways. She finds that she barely needs to think about it, quite soon: that she can become her beautiful black Siamese cat with hardly a whisper. One day, she even tries it out in the library, and not a single person notices the change, though admittedly she does hide under the table. She can switch to and fro as often as she likes: no tiredness, no pain, no gloop, no noise, no problem. She has to resist a strong urge to write to the authors of various paranormal tales to tell them they've got it all wrong. She does make sure, after a rather embarrassing incident where she needs to disentangle herself from a cheap t-shirt, that all her clothes are pure natural fibre. It was sheer luck that they were that first time. She makes sure that phones, and similar useful items such as wallets and their contents, change with her. She buys some comfortable cushions for her couch – and a scratching post, which she keeps in her bedroom – and finds that after a stressful day it's surprisingly soothing to be a cat. She has a cat flap fitted: so discreet that it's barely noticeable.

The panther (she's done some research, and she's pretty sure it's a panther) is also gorgeous, with an edge of concentrated lethality which Kate really likes. It gives her confidence that no matter what happens, she's got a secret advantage. She doesn't use that form nearly as much as her cat, but if she's had a really frustrating day, its claws ripping through the post helps. It – _she_ – likes her meat cooked rare, now.

What she doesn't have is a boyfriend. Her odd – er – _quirk_ is not something she wants to explain, and, her trust levels already at an all time low courtesy of Sasha, who got her into this mess, and her father's alcoholism, she's not inclined to believe that anyone would ever keep it quiet. She's also rather uncertain that she can control it. Orgasm, after all, _should_ involve a considerable loss of control, if you're doing it right. She buys a toy and works that one out, too. She doesn't change, even at peak moments. One less problem to worry about.

* * *

The Academy is _tough_. Very tough. But, hiding in work from her father's continued and, it seems, inevitable dissolution in alcohol, Kate not only survives but flourishes, eventually coming top of her class. More importantly, she's made it through all known blood, health and medical tests without a single flag being raised. So now she's Officer Beckett, rookie.

A couple of months after being signed off by her training officer, Beckett (no-one ever uses first names, and so she's gradually falling out of using hers, even in her head) is tapped up for a Vice operation. This is a bit more interesting than the usual Dumpster diving and canvassing, though, because they want her to be Russian (that'll be fun) and it's part of a much bigger sting, involving a couple of other precincts. She's moving precinct soon, so this is by way of a last hurrah.

She will _not_ be sorry to move on from this Vice operation, though realism tells her she's going to be doing a lot more of them if she doesn't screw up here. (She's desperate for Homicide, but she needs to serve her time before she's even fit to apply for that. Means she _can't_ screw up, because she can't bear to lose that chance.) The op is down in the Meatpacking district, and it would be chilly even if she was wearing more than two oversized belts and six inch dominatrix heels. The caked on make-up is protecting her face from the wind-chill, though. She wishes she could become her beautiful cat, who at least has a fur coat to keep her warm. She's been staking out this patch for two or three days, passing on everything she notices. _Eyes on the ground_ , her boss had called it, so she guesses she can stand the shivering, and the commentary.

Suddenly it all gets loud and busy with red-and-blues and sirens and cops of all sizes and shapes flooding the area. Beckett, leaning on her lamppost, watches with interest, right up till two of the cops try to arrest _her_. No way. She's undercover. Oh. She has to _stay_ undercover – and then one of them cops a feel, and she loses her temper. He's on the floor in a hurry, his likewise-wanderingly handed pal follows, but suddenly there's a giant uniformed officer right next to her. Beckett, thoroughly displeased with the whole situation and unable to change into her ferociously lethal panther to treat the unprofessional cops as they deserve, doesn't hesitate before she takes a kick which only just misses his testicles (dammit!) and then follows up with a textbook haymaker to the solar plexus.

 _Ow!_ That freaking _hurt_? What is this giant anyway? It's bigger than a bear. Still, she's got to stay undercover till she's well out of view of any of the targets and if this guy is with the two who tried to feel her up it'll serve him right. She tries for another punch, which Bigfoot here catches, and suddenly she's head down over his shoulder, trying and failing to hit him hard enough for him to notice and swearing at him up hill and down dale in two languages. She very nearly shifts to panther when he swats her ass, though she manages to resist and lands some scratches and at least one hit that makes him huff, but eventually she stops. The Bigfoot cuffs her, and stuffs her into his cruiser.

* * *

 _Thank you to all readers and reviewers._

 _Guestt, Hawkie, and RogueOne - and all other guests - much appreciated, and here is the story quite a lot of you wanted to see._

 _As you may have noticed, the site is not putting updated stories to the top of the list, and isn't necessarily sending out alerts either. This story will be updated at around 2pm EST/7pm BST on Tuesday, Thursday, Sunday, Tuesday; which you will work out means that it has 5 chapters._

 _A small note: this is both a prequel to Felis Felix, and also Beckett's point of view of the same events. It would be more than a little helpful to have read that first._


	2. Chapter 2

**Chapter 2: Looking for a kitty**

"Er… hey?" she says, when the cruiser doors are shut. "Um, I'm Officer Kate Beckett, badge number 41319. I was undercover for Vice, but I'm at the Tenth Precinct."

"You're a cop? Li'l bitty thin' like you?"

"I'm not little!" she says indignantly. "You're a monster." Maybe he's a bear? It would be nice if it weren't just her.

"Nah," the mountain rumbles back. "Now then, I'm Officer O'Leary, an' I think I'd better find out if you're tellin' me the truth." He makes a call, listens for a moment or two. "Yessir," he says. "Yeah. Dark hair, dress matches. Badge 41319. She ran it right off, like we do. Yeah, that's the name she gave. Yessir. I got her here. She's okay."

He cuts the call and turns around. "Guess you're who you say you are. Let's go around a bit an' when we're clear of the funfair I'll take the cuffs off an' you can come up front. We oughta get acquainted a bit, seein' as you been tryin' to beat me up an' I swatted your ass for it."

"Doesn't that make us practically siblings?" Beckett asks him pertly.

"Prob'ly," Officer O'Leary grins.

He makes a few quick turns and pulls up, and a few seconds later she's unlocked and slipping into the passenger seat.

"Um… sorry about that," Beckett emits. "I didn't know what to do, and I was told to stay undercover till it was all over."

"'S okay. Ain't no way a teeny little thin' like you was gonna hurt me."

"Hurt my knuckles trying," she grouses.

"Ain't my fault. Anyways, pleased t' meet you, Officer Beckett. How long you been on the job?"

She counts on her fingers. "Ten weeks since my Training Officer signed me off. First Vice operation. Nice to meet you too." She shivers. "Could you turn the heating up a bit? It's cold out there."

"Not surprised you're cold. You ain't wearing more'n two handkerchiefs." He turns the heat up. "I'm O'Leary. I'm with the Sixth. Been there a year."

"Sixth? That's where I'm moving to next." She smiles at him. Oddly, it doesn't have the usual effect. Also oddly, unlike the two meatheads, he'd been strangely, um, calm. Or something like that. "Do they know you're gay?" she blurts out.

Officer O'Leary chokes. "Say what?"

"You're gay. Aren't you?"

Compared to her secret, that's tiny. Enormous Officer O'Leary, however, is not impressed. "How'd you know that?" he growls. "No-one knows that."

"Um…" Beckett says, a little scared in a way that she hadn't been earlier. She reminds herself that she can be a full size panther, and thus fatal to any Officer Bigfoot O'Leary before he can reach his gun, and decides on truth. "You didn't cop a feel. All the others did. Um… I won't tell anyone." She decides to share something of her own, to prove it. "Um… I joined the NYPD 'cause my mom was murdered," she emits. "I wanna get into Homicide, so I can solve it."

He stands down, somewhat. "Okay. Secret for a secret. Won't be any fun for either of us if those get out." A massive hand is extended to Beckett, who puts hers in it and contemplates its likely crushing. In fact, O'Leary enfolds it with considerable delicacy, and shakes very gently. "You say you're comin' to the Sixth?"

"Yeah. Wanna tell me a bit about it?"

"Okay…"

When she reaches the Sixth, a while later, it's good to have a friend. But she still doesn't tell him her real secret, though O'Leary knows more than anyone else alive about her life. He's there when she has to pick her father up, though she tries to pretend he isn't, because she can't bear to admit that part of her life. Beckett buries herself in work, after that, and soon enough she and O'Leary, now accepted (though still uniforms) as pretty much partners, are working together a lot.

They do stakeouts together, and have each other's backs, and give each other a really good cover and plus-one, much to everyone's amusement. No-one calls them Bleary, though, at least, not more than once. They're even allowed to soften up the lowlives in Interrogation, which is great fun, though Beckett often thinks that she'd be able to scare a confession out of anyone if she could only turn into her panther and smile. Well, bare her teeth.

"Beckett, O'Leary!" the Captain calls one wet evening.

"Sir?"

"You need to get along to support Detectives Clary and Hill." They're given the address of a downbeat site off West Street, between Leroy and Clarkson, and get moving. O'Leary drives. He always drives, which annoys Beckett intensely, but he claims seniority – and size. Despite their sparring, she's never going to win that argument.

The site is dingy, smelly and, most critically, appears to be hosting a minor war, not improved by the lack of street-lighting and the driving rain. Unusually, but definitely helpfully, none of the non-cops has pulled a gun. In fact, Beckett thinks that there are at least three sides fighting, with the detectives currently standing back, watching for an opportunity.

"O'Leary. Beckett. Somewhere in there are a couple of guys we want a little chat with. O'Leary, break it up. Beckett, we'll help. Try not to get hurt."

O'Leary sniggers. "She spars with me," he says.

"Okay, try not to hurt anyone else." He looks at the free fight. "Hill'll go for the one with the black hoodie, I'll take the luminous yellow. O'Leary, you get the big guy outta there and down. Beckett, see that little one – he's yours." He pauses. "That's where we start. No guns 'less we hafta. If you can take down anyone else, do it."

"Police, _freeze_!" Hill yells.

Nothing happens. "Go!"

Beckett follows O'Leary in, and, not for the first time, finds that everyone turns on the cops, united against the enemy. She targets her man, but it's all getting very, very messy. Still, they're winning. At least, she thinks so – right up until five more toughs arrive and wade in. At that point it all starts to go horribly, horribly wrong. She's so busy trying to survive that she doesn't see O'Leary being jumped by three of them; doesn't see two more on Hill and on Clary; doesn't see much after two of them rush her.

She changes, hiding it in a duck-and-roll move that the drill instructor would have slated her for, and scarpers out of the fight round the corner: changes back and calls for urgent back-up; then goes back in. No-one's noticed her absence. She wades in to help O'Leary, who's staggering and shaking his head, and together they manage to get one man cuffed and out the game before moving on to the next. IT's all so fast and furious that she hasn't time to think, and then the reinforcements arrive and suddenly everyone's on the floor.

"Good work, Beckett," Clary says. "Quick thinking to duck out and call. Lotta guys wouldn't'a done that."

"Thanks." She runs fingers through her dripping hair, and winces.

"Let's get back and report."

"How'd you manage to get outta there long enough to call it in?" O'Leary asks, once they're in the car.

"I'm not a mountain," Beckett points out. "They were all concentrating on you, so I had a chance when I went down and I took it."

O'Leary briefly looks as if he wants to say something, but doesn't. Instead he touches his boulder-size skull, very cautiously, and winces. "Ow. That punch was somethin' else. Let's get back. I think I've had enough of this."

"Me too. I took a few hits there."

"You oughta get checked out. Li'l thin' like you, you're fragile."

"I will if you will," Beckett says, and thinks hopefully of a nice hot bath and then some quality snuggling as a cat. Until she became one – another point where all the books are wrong – she'd thought that changing shape would heal all hurts. Hell no. And she doesn't even have a nice boyfriend to pet her and take care of her. Humph. For the first time ever, she wishes that she could share her secret with O'Leary, but… he's pretty much a dog person, and anyway, two people can only keep a secret if one of them is dead. She doesn't want to have to kill O'Leary, and she certainly doesn't want to be dead herself.

"I don't need no ER," O'Leary drawls.

"Then I don't either. Let's finish up this paperwork and get out. First one's on me."

"Molloys," O'Leary says. Beckett grouses and grumps and grumbles and grouses some more about the location, and utterly fails to change his mind.

By the time they get to Molloys, Beckett is creaking quite spectacularly, and rather wishing she'd never suggested a soothing drink. She's on soda, as normal, O'Leary on O'Douls.

"How do you do it?"

"Huh?"

"How're you so invisible on stakeouts? I can't see you at all even when I'm lookin' right at you."

Oh shit. This is not a good question at all. Beckett sips her soda, preserves a totally bland visage, and thinks frantically. Saying _I change into a black cat and no-one notices a black cat at night_ is not a good answer.

"Are you sure you're looking at me?" she smirks. "You might not see me when you're looking down through the clouds."

O'Leary laughs. "Mean, butterfly" –

"You _what_ now?"

"Butterfly. You not heard that yet?" He grins, as wide as the Nile delta. "'S your nickname. Butterfly."

" _Butterfly_?" Well, at least it's not _cat_ -related.

"Yep," he drawls far too happily for Beckett's taste, and snickers, vibrating small objects such as glasses, tables and chairs. "Butterfly."

Beckett scowls. She'll turn into her panther and sneak up behind them all late one night and bite their sexist asses into shreds.

"Wanna know why?"

"I guess," she grumps blackly.

"Waaalllll, it ain't because you're pretty. Fact is, that got nuthin' to do with it. Though you do look quite nice when you don't have bruises an' you've brushed your hair."

Beckett growls, and is quite horrified to realise that it's far closer to the panther's voice than it should be.

"Just 'cause you've got no hair to brush," she snips.

"Showin' off my manly profile," O'Leary returns easily. "D'you wanna argue, or d'you wanna know 'bout your nickname?"

"Nickname. But if I find out you started it" – O'Leary stares blandly back at her, massively impassive – "I'll…" she fails to find a credible threat. He's too big for her to make any impression on him at all.

"Some of the guys were watching you in Interrogation, an' they liked the sight" – oh, _ugh_ , O'Leary. That's just _icky_ – "Said it reminded them of Muhammad Ali." _Oh. Okay then… I might not stalk and scratch them after all_. "An' someone said 'float like a butterfly, sting like a bee' an', waaallll, that was it, y'know?"

"Huh," Beckett says. "I still don't like it, though." On the other hand, it's effectively distracted O'Leary from her stakeout invisibility. Oh. It hasn't.

"So how do you hide like that? I mean, you're a long way down an' all, but…"

"Just good luck. Dark uniform, cover up the shiny belt buckle, hide the cuffs, mess the hair so it blurs my face – and stay away from street lamps. 'S easy."

 _Now please stop asking questions_.

"I guess," O'Leary says doubtfully.

"I'm just better at hiding than you are," she smirks smugly. "You'll just have to practice being a tree." An incautious move makes her yelp. "Ow. I think I'd better go home and take a long hot bath and slap on some Icy Hot."

"Yeah. Me too."

They wander out. O'Leary, as ever, insists on walking her back to her apartment. She just can't shake that habit of his, though it's entirely unnecessary, and sometimes, as today, annoying. She feels obliged to invite him up for coffee and takeout, and right now she just wants to be her cat. Fortunately, he refuses.

And so time goes on. She can sense O'Leary watching very carefully on stakeouts, but she's even more careful about her changes. If the cat comes from one direction, Officer Beckett appears from another.

But then there's the day they get caught out again. She's due to leave the Sixth shortly – as is O'Leary, who's being transferred to Central Park. She's been picked up by the Twelfth, and Captain Montgomery's promised her a shot at Homicide if she puts in another solid year of uniformed work. They're pounding the streets late at night when they spot trouble: a drug deal going down and going wrong. Of course they have to intervene – it's just a shame that as they do another gang rolls in and gets involved. She doesn't have an option: even O'Leary's size and strength is hopelessly overmatched. So she shifts, exits the melee like an – er – cat on a hot tin roof, whips round the corner and calls it in, and returns.

Afterwards, both of them bruised and battered, O'Leary is both suspicious and curious about how she managed it, and cross-questions her relentlessly. She obfuscates until he's sufficiently baffled that he drops it, but he regards her very oddly for a while, until they depart for pastures new.

* * *

Six years later, during which they've drifted: never the same after she wouldn't collect her father from O'Leary's shop, drank herself unconscious under O'Leary's watchful eye and he had to take her home: six years later when she's chasing down a drunk and he's got him in his cell: six years later O'Leary meets her thoroughly irritating shadow, and likes him. Not just likes him, but _really_ likes him. Platonically, of course. O'Leary's head-over-heels with his Pete.

The instant bromance is not necessarily a good thing. Castle is insatiably curious, and O'Leary knows all the stories. Well, except the real one. No-one at all knows the real story. No-one ever will.

And yet. Regardless of Castle's total annoying-ness, there's not so much a spark between them as a lit fuse leading into a barrel of gelignite. He's unutterably sexy (not that she lets him know she thinks it) and he really, really makes life fun. She can't stop considering how good it would be if she simply let herself fall into his arms. Well, bed. She's sure it would be great.

She's also sure it would break her heart. She'd never be able to be all in, because even on a few weeks' acquaintance she is perfectly certain that Castle is completely incapable of keeping secrets. Every thought, no matter how insane, which enters his brain falls out of his motorised mouth. She can't hit a relationship where she can't go all in. Her whole relationship with Will had foundered on – well, not _only_ on her inability to tell the truth, because he'd wanted Boston and she hadn't – but it certainly hadn't helped.

But it would be so good. She watches his hands, more often than she should do, and thinks that those wide, strong fingers would pet her most excellently, in any form. She sees him with his daughter, which opens her eyes to a real man, behind the playboy smarm and charm: a man who's kind, caring and loving; a man who wouldn't simply be about the sex.

Every day, she falls a little further – and every day, she's brought up short by the weight of her secret. She even mentions her mother and father, and instead of making flippant comments he takes it seriously – and never mentions it to anyone, including her, ever again. Maybe, just maybe, he can keep secrets after all. She begins to hope.

And then, of course, he screws everything up by nosing into her mother's murder when she'd told him not to, and it all falls apart. It _proves_ that he can't keep out of matters that don't concern him, and so that she can't trust him with her secrets.

That night, for the first time in three months – for the first time since she'd met Richard Castle – she turns into her panther and rips the scratching post apart: changes back, very late at night, and goes out to Central Park to wreak havoc not just on the wildlife but a collection of would-be muggers, dealers and other forms of criminal life.

She doesn't kill or injure any _people_. Scared them shitless, but not a single one of them was touched. The same could not be said for the squirrels and other urban wildlife. Each animal corpse has Castle's face, until she tears it apart with bloodied teeth and claws. Left to its own devices, the panther is quite content to sate her fury and heartbroken disappointment in bloodlust.

She takes that same option quite often, over the summer. The team look at her tense, tired face (late night forays are taking their toll) and don't say a word. Killing squirrels helps. It stops her crying over what might have been, when she goes home, as unhappy as when she left. No-one understands why the crime stats are so much lower round Central Park than in any other year, or than any other precinct.

She's quite sure that Castle's as incapable of apologising as he had been the first day she'd met him, when Montgomery insists that he's allowed back for book promotions and a body drops while he's there. He's insufferable. And yet she's still attracted, much as she hates to admit it.

He _apologises_. He comes back into the precinct after she'd bade him farewell for ever, telling him he was selfish and pushy: spilling out her angry hurt. He comes back, and apologises with total sincerity and no expectations at all that she would accept it. She nearly faints with shock, and even more nearly changes into her cat with sheer astonishment and embarrassment.

"Castle. I'll see you tomorrow."

His smile blazes through the bullpen. That night, she doesn't need to go criminal-scaring and wildlife-killing. That night, she dreams of him petting her in every possible form, and then making love to her in every possible way.

A week or two later, obliquely, she raises the subject of shapeshifters, by way of claiming to have read a ridiculous book, when they're pretty much back on good terms and comfortable with each other again. Well. Comfortable possibly isn't the right word. Castle frequently looks less than perfectly comfortable below the belt, and she is often rather more damp than comfort would indicate. Naturally, Castle is delighted with the idea of shapeshifters, and bouncily enthusiastic. She should have expected that. Castle is thoroughly bouncily enthusiastic about all forms of supernatural, paranormal, and downright weird non-existent entities.

Except that _this_ paranormal entity does exist. And _this_ paranormal entity is pretty damn tired of being single, and keeping secrets. _This_ paranormal entity wants to be petted and cuddled and stroked and kissed and taken to bed and comprehensively reduced to a melted mess of hot lust and soft loving. Or taking him to bed and comprehensively reducing him to a melted mess of hot lust and soft loving. Either way, she wins. She casts a glance at his hands, which could do so many deliciously wicked things, and then a rapid, unnoticed flicker over the rest of him. Her cat could curl in his lap, or drape over that wide, warm shoulder, or curl into the space between shoulder and neck. He never stops fidgeting, so he'd pet her cat continuously. It would be so good. She looks at his fingers, again, and tries very hard not to blush.

"I've got a signing session tomorrow," he says. "I'm reading, too. You should come along and listen." He smirks happily. "You'd love it."

"Really?" she says, raising a quizzical eyebrow. "Why?"

"You love my books, and you'll have the chance to admire my ruggedly handsome physique" – she snickers – "and listen to my deep, sexy voice."

"Ri-ight. I have to look and listen to you all the time here, and you think I should spend my time off doing it too?"

"I could make some better suggestions, but you'd hit me," he says, and waggles his eyebrows insinuatingly. "Which is just so unfair, because you'd enjoy them even more."

"Shut up, Castle."

* * *

 _Thank you to all readers and reviewers._

 _The site is still appallingly flaky as regards sending out alerts and/or putting updated stories to the top of the list. The next instalment of this story will be on Thursday at 2pm EST/7pm BST, for those interested._


	3. Chapter 3

_A/N: Courtesy of the site mess ups, you might have missed chapter 2, which was posted on Tuesday. Probably best to read that before this one._

* * *

 **Chapter 3: Cool cat**

On Saturday night, she gets a cab to the Rizzoli bookstore, listens to the reading without being noticed by anyone for a minute or two– perfect, it's about five minutes till he takes a break – slides silently into the alleyway behind it, looks at her watch again, and changes to her pure black cat. She's invisible in the gloom.

And there he is. Wow. Oh oh oh _oh_! She'd never thought about how much more her cat form would notice simply from his scent. _Oh, oooohhhhh!_ She likes his aftershave, sure, but _ohhhhh_ her far more sensitive cat nostrils are overloaded and it's all going straight to her core. She knows the minute he sees her, straightening from the wall, but when she slithers and curls around his legs – oh, _now_ she knows why cats do that: that feels _fabulous_ – he doesn't try to take liberties, he simply pets around her ears.

Oh. Oh, _yes_. Oh, those _fingers_. He could be playing with her breasts. _Oohhhhhh_. If she were human, she'd be close to orgasm already. Even as a cat, she's pretty close. He strokes down her spine and she arches into the touch, utterly undone by the sensations. This might just have been the best idea of her entire life to date.

And then he picks her up: strong hands holding her, and lays her against his shoulder in just the way she'd dreamed about, and keeps petting. And he's talking: compliments and flattery, and in cat form the sound of his voice is almost as irresistible as the delicate, erotic (not that he knows that) touch of his hands. She snuggles into that broad shoulder and warm neck, breathes in the druggingly sexy scent of Castle and his cologne, and starts to purr continuously. He's… _ooohhhhh_ , who _cares_ about _words? Just don't stop petting me, Castle_. She's pretty certain she's just come, because he's been playing gently with her ears again.

"Mr Castle?" some unwanted person interrupts her blissed-out haze of total sexual satisfaction. "Mr Castle, it's time to restart."

Who is this idiot? She wants to bite him. Hard, and fatally. He shouldn't be interrupting them. He – idiot – shouldn't be causing Castle to put her down and stop that amazingly wonderful petting and stroking.

"I've got to put you down. They want me to go back to finish the reading, and I can't disappoint my public. It's not nice." He very gently detaches her. Beckett-cat mews, very softly, and only just stops herself running her claws into his very expensive clothes to stop him putting her down. She wants to stay right where she is. She feels astonishingly safe, and warm, and comforted. She hasn't felt like that for over ten years.

"Guess you won't be here when I'm done," he says, and her sensitive ears pick up a note of disappointment. "Bye, beautiful."

Oh, she'll be there. Oh yes. She follows after him, and confidently takes possession of a space in front of the chairs where she can watch him.

About five minutes in she realises that she's mooning over him like a lovesick teen, and, embarrassed even as a cat, washes a paw and stalks away, tail flicking dismissively. She gets as far as a very private corner, changes back to Beckett, and goes in to listen to the rest of the reading.

She is amused, delighted, and astonished in almost equal measure to discover that he is very concerned about the cat – her – and that he is quite clearly a cat person. Perfect. Or possibly purrfect. But then he has to attend to the fans, so she slips away.

She means to slip away. She's not going to go back as a cat and be petted and cuddled and stroked and left blissed out again tonight. She even leaves the bookstore – just as far as the nearest coffee bar for a quick hit of common sense before she goes home. Even caffeine doesn't restore her normal sense. She simply _cannot_ get over how good he made her feel.

She goes back to the bookstore.

She lurks in that same private corner and changes back, and stalks back into the reading area, watching all the drooling fans with deep dislike. She could empty the room in an instant, she knows – and right now, she's almost failing to remember why she shouldn't. Castle is _hers_ , and these crowds of women aren't getting a look-in. He might not know it, yet, but she's not letting him go now.

Finally the fans disappear, Castle spots her, and shortly she's in his lap, drowning in petting and snuggling and total pleasure, and then he takes her home, stroking all the way. Even if she were a real cat, and thus unused to cabs, the stroking would keep her pinned in place. Oh, those _fingers_. Ohhhhhh.

Oh, no. There will be no bowls on the floor here. That's not dignified. She regards Castle, who takes the hint (and the bowl which he'd been about to place on the floor) and puts it on the desk, near his laptop. She laps up the milk, and then poses perfectly on the surface. More stroking occurs. She drifts off into a sensual haze, drugged by his glorious aroma.

He's _named_ her. Wow. He must really like her cat. She likes the name, too. Suitably elegant. She indicates that more stroking would be appreciated, and he responds immediately. Good. He's perfectly trainable. Very responsive. She thinks about whether he'll be equally responsive in bed, and then leaps for his shoulder again.

Later, she indulges in looking around his bedroom, while he's promising her a home. He really is a cat person. Of course, she has a home of her own, which Castle has occasionally visited to discuss cases. Lovely big bed, mmmm. She jumps on to it, and discovers it to be nicely firm. She wouldn't want to sink into the mattress. After she's used the bathroom – even as a cat she uses the bathroom – she returns, stalks on to the bed again, and listens to Castle promising to introduce her to herself. Not going to happen.

On the other hand, the note in his voice is very interesting indeed. It's wistful, and just a little adoring. Adoration is good. Very good. She snuggles into his neck and indulges in some more breathing in of very sexy essence of Castle.

Castle, she thinks as she curls up in the crook of his neck, in his bed, might think that he's acquired a cat. But everyone knows that you don't own a cat: they own you.

She could get used to this: sleeping snuggled up to Castle. But much as she doesn't want to, she needs to go. She can't be both here and in the precinct; and unbelievable ability to make her cat very, very happy notwithstanding, she needs to have a lot more evidence before she lets the truth out.

* * *

Castle spends the morning complaining and worrying about the cat. Beckett plays along, never twitching a hair at his commentary. She can play this game all day.

"You're really upset," she says, wondering what he'll say, and yes, okay, she's fishing a little. She's allowed.

"Yeah. She was gorgeous." Gorgeous is good. Oh yes. Carry on with the compliments, Castle. She fishes a little more, and is then very grateful for an excellent poker face.

"I guess I fell in love" – she doesn't hear the rest. How can she be so instantly jealous of her own self? She's _hurt_. She snarks, to cover it up. He's in love with the _cat_? He's not supposed to be in love with the damn _cat_ , he's supposed to fall in love with _her_. Even if she is the cat. Her head hurts.

Beckett goes home at the end of shift, and takes out her venom on the scratching post and as a panther. She will not go to see Castle. She won't. She absolutely will not.

Half an hour later she's in a cab to Broome Street. Long enough after the cab decants her that no-one's looking, she nips into a handy alley and changes, then stalks into the doorway of Castle's block and glares at the doorman until he notices her. He looks at her in surprise, and then lifts the house phone. She sits perfectly poised and precise.

Much to her amazement, Castle is down in record time, scoops her up and doesn't cease to pet her – ohhhhh, round her ears, ohhhhh, more please Castle, don't _stop_ – while simultaneously berating her for disappearing and worrying him. The note of concern – and the petting, and feeding of treats, is all very encouraging. Definitely very trainable, her Castle. She would think a little further, but he's still fondling her ears and that is still sending her into sexual meltdown.

Vet? No way, José. No vet. How the hell is she going to get out of this? She hasn't a clue. Castle doesn't even have the decency to go to the bathroom so she can sneak out before he can take her to any _vet_. This is a _disaster_ , she thinks, in a cab on his knee on the way to a freaking _vet_. No amount of ear-fondling and sexual meltdown is worth this – _ow_! That shot really hurt. She growls viciously. In speech, it would have been a string of profanity. She won't be petted when he's just really hurt her. She makes as if to scratch.

"C'mon, Onyx. That's not kind." Damn right it's not kind. He _hurt_ her. "It's just to keep you safe."

What the hell? What has he just done? Realisation dawns. That rat _bastard_ has just chipped her. What the hell is she going to do now? _Chipped_? She's not a pet. She is a senior detective with a shield and a gun and _nobody_ puts a freaking _chip_ in her. She will kill him.

She can't kill him. How is she going to explain as Beckett that he chipped her as Onyx? Even Castle would boggle. He's stymied her. _Rat_! At least he's warning her about the shots. She doesn't like them, either. Ow, ow, ow. Vets are even worse than doctors. On the other hand he's fussing and petting her and _ohhhhhh_ , that's better than massage. She becomes bonelessly spread over his shoulder.

By bedtime, she's wishing that she never, ever had to leave. Castle's constant petting is a far better use of his fingers than his constant fidgeting in the precinct, and all of it is wriggling down her spine to pool and heat at her core. No wonder cats always look so self-satisfied when they're being fussed over, she thinks. They're blissed out on multiple orgasms. It almost makes up for the chip and shots.

She's happily curled up, tucked into his pillow, luxuriating in the sensuous (not that he knows it) petting, when he starts to talk to her. She supposes she should have expected it. Castle _never_ stops talking, except when asleep.

She didn't expect _that_. Castle is pouring out his heart to her. Well, _now_. That's an unexpected benefit. He – good Lord. He really cares that he upset her. Good Lord. She provides some feline, tactile reassurance, and snuggles up to him totally content. He pets her till he falls asleep.

She really doesn't want to go home, but she has to. She _wants_ to stay cuddled in and wake up next to him – even as a cat – and be petted some – lots and lots and lots – more. She's decided very quickly that she loves petting and snuggling. She slides silently off the pillow, sulking about the necessity, and sneaks out of the bedroom and to the outer door. Her sensitive ears listen hard, and hear only the deep breathing of three people asleep. She changes, opens the door with no noise at all, slips out and shuts it equally soundlessly, changing back to Onyx as soon as she has.

In the morning she is very tired and very sore. The shots, just as human shots would, have left her with a vague malaise, and the spot where the chip is (she curses internally) still _hurts_. Castle is being both annoying and suggestive, and since her discomforts are all his fault, she doesn't scruple to take her disgruntled mood out on him. He humphs and then chases down a different trail.

"I know you remember my cat," he says sulkily.

" _Your_ cat?" She's not _his_. She's her own person. She's not having this possessive behaviour. She's a mature woman (and feline) and being referred to as _his_ is inappropriate.

If only it didn't arrow straight to her core and send her damp and hot. Even if he doesn't know he's talking about her. She really shouldn't be thinking about how _exactly_ she could be his and how good she'd feel when she was and – _stop_.

"Yep," Castle states firmly. "My cat. Chipped and everything. I even got her all her shots. She didn't like it much, though. She growled and hissed at me. She sounded a lot like you on a bad day." _What?_ Beckett does not growl and hiss – in human form, and she never has bad days. "Anyway, she's mine now. I'm not taking the chance someone else steals her."

More ridiculously possessive statements. Huh.

But it is very nice indeed to be wanted that much, even if it's as a cat. In fact, taken with last night's commentary on her human form, she might even begin to think that he feels a lot more than friendship.

She'd better go back tonight. She wouldn't want him to worry about her cat. The petting doesn't hurt, either. She's had more orgasms in the last week than in the last ten years, if you exclude self-generated ones.

And besides, she is absolutely _insanely_ curious to see what he might reveal when he thinks he's talking to himself.

This was definitely the right thing to do, Beckett-Onyx decides when the first thing Castle does is fondle her ears. He even gives her coffee. She's nearly sorry for spitting at him when he'd caught the sore spot on her back. And then he goes back to pouring his heart out.

"I love her mind. It's as hot as the rest of her." _You damn well should love my mind. But it's nice to know it's not just about the looks and the hot body._

"I guess she wasn't feeling well with that bite. I hope she isn't sick – but if she was, I could take her chicken soup and mop her fevered brow." He stops. "Jealous?" Oh. She hissed. Not jealous, she just doesn't like company when she's ill. Or chicken soup, for that matter. She can't be jealous of herself. That would be silly. Or schizophrenic. "I wouldn't be. You're here. She isn't. No chance she will be, either." He sounds quite deeply miserable about that.

"I don't even know how to get her to come out on a date. I've given up asking." _Don't stop asking, you idiot! Aaarrrgh_. "Every so often I think she's interested" – _damn right I am, now that I know you're not looking for a one-night stand_ – "and then someone interrupts or there's a murder or the moment's lost some other way." _Yes, I've considered shooting Ryan and Espo too. The Cockblock Twins_. "I just wish I knew what she liked: movies or theatre or even grand opera. I'd even listen to Country and Western music, and I hate that. Just _something_ to break the ice." _Not Country and Western. I hate that. But anything else would be very acceptable._

Right. He wants a date. Well, that can be arranged. Especially as he sounds even more affectionately hopeful than earlier. She purrs at him, and snuggles in a little more, and hopes that he takes it as encouragement to have another go at asking her on a date.

Beckett has to say to herself, as she sips her coffee the next morning and works through her in-tray, that sneaking round Castle as Onyx-the-cat has to be the best idea she has ever had. She's found out more about who he _really_ is in a scant few hours than she'd learned in six months of being human, and the more she learns, the better she likes him. Really, really likes him.

Liking is, as ever, at its daily peak (for public purposes: the private petting is a whole different and orgasmic ball game) when he arrives with coffee, full of the delights of his cat.

"I need them to install a cat flap." _Excellent plan. Especially for sneaking out without needing to be human for half a minute._ "One of those hi-tech ones that only opens to let her in when it senses the microchip."

"Won't that mean she can get out?"

"No. I researched it. There are one way types." _What the hell? You idiot! That's no use at all. I need to be able to leave! Dumbass! Why did you have to be so freaking overprotective of a cat? Aaaargghgghhh!_ Not one jot of her feelings shows on her face.

And then he asks her round for dinner, claiming he wants her to meet Onyx. No need for that. She meets Onyx every morning in her mirror. He's going to be disappointed in that respect, but still, she's got what she wanted, and with her secret knowledge of his real thoughts and feelings, she should be able to make sure that matters move forward. Not too fast, however. She's not sure she'd ever recover if he broke her heart now.

She comes away from dinner with a _date_ , and a hug. Well, she thinks it was a mere hug. It's astonishing that she'd managed to leave the loft. Castle flavoured hugs are _amazing_. Almost as amazing as petting. She could live with a lot more of those hugs, and a lot closer approach to more than just first base. It had been incredibly difficult not simply to kiss him and see what happened next.

On the other paw, she has an answer to that…

She takes the elevator down, leaves the building, walks down the street to a convenient alleyway, shifts to Onyx, and immediately returns. Castle is predictably pleased to see her – and she gets to be stroked, snuggled and petted to her heart's – and loins' – content. He should have kissed her, though. Why didn't he kiss her? _Idiot_. He even told her (well, Onyx) that he wants to kiss her. Hmm. Some encouragement required. That's for tomorrow. After all, she's got the date she wanted…

Anyway, since the hug had definitely indicated some very nice musculature under Castle's shirt, she's going to pay some proper attention. She ensures that she gets to the bathroom first, and therefore is perched proudly on the pillows when Castle undresses. He has her _full_ attention. Ooooohhhh yes. Ohhhh that's very nice. _Very_ nice indeed. Why wasn't she watching previously? That was a total mistake. Eye candy – nope, this is one hundred percent pure eye heroin. More, _please_.

The following day is an absolute freaking disaster. Their raid on the bad guys went completely to hell when there were _four_ of them – she will have the surveillance team's heads, balls and guts for that screw-up – and she's taken a hell of a beating. She whimpers her way home from the hospital, nothing broken but in severe pain all the same, changes, and finds that she's just as damaged as a cat or panther as she is in human form. It hurts, in all forms.

But. Unlike every other time, _this_ time she does have someone who'll pet and cuddle her and make her feel better – or at least take care of her. All she has to do is get there, and Castle will do all the rest. Even the thought of moving hurts, though. She feels worse now than she had an hour ago. If she wants Castle – and she very definitely does – she needs to move now, because in another hour she won't be able to move at all.

The cab decants her alongside the same alley that she's been using all along. Beckett staggers out of it, wincing with every move, leans on the wall to prop herself up and changes. She makes it just as far as the doorway, and can't restrain her anguished yowls any longer. The doorman hears her – half of Manhattan can probably hear her – opens the door; she takes two steps inside, and collapses on the floor. She's here, and that's all she can manage.

* * *

 _Thank you to all readers and reviewers, especially guests._

 _Hawkie, no, I haven't seen that anime._

 _In case the site fails to send alerts again, the next chapter will be at 2pm EST/7pm BST on Sunday._


	4. Chapter 4

**Chapter 4: A cat so clever**

Castle turns out to be astonishingly good in a crisis. She's cuddled in his arms and on the way to the vet in mere moments. She's so sore she can't even appreciate his intoxicating scent and body, but she certainly does appreciate his decisive actions and total care for her. It occurs to her that if she were hurt on the job, he'd be very likely to care for her just as effectively. When he takes her home – home? She must be hurt. It's not her home – she is placed very gently on a pillow, which soothes her hurts as the anaesthetic wears off, and gratefully falls asleep.

She doesn't notice a single thing until the next day, and she spends most of that asleep too, lost in the soft comfort of Castle's care and delicate petting. She can't do anything about Castle's texts to her, which leaves her feeling guilty: he's so clearly concerned, but she's far more interested in his evident desire to take care of human-Beckett if only he were given the chance. Well, he might just get the chance. How has she never noticed how beautifully, adorably protective and caring he really is?

Ah. That would be because he's acted the arrogant, jackass playboy non-stop for six months, nosed into her mother's case without asking and indeed after being told to butt out, and loses no opportunity to flirt, tease and annoy. Silly man. If he'd only shown her this side of him, she'd have understood why he nosed into her case: he wanted to make it all better. It's so clear, now, even if he's never said it.

She'd answer his texts, but she can't guarantee that she'd get any safe length of time without him, and explaining is not something she wants to do just yet. When they're a bit further on. When she's managed to start a proper relationship in human form. When she's sure – though she's getting more sure by the minute.

The next morning, she feels a lot better, though she really couldn't say that going to the precinct is in any way desirable. She sits on her own chair – Ryan really deserved to be bitten: _cute_? She is not _cute_ , she is _elegant_. _Cute_? – until Montgomery comes along and objects, humph, but it gets her on to Castle's shoulder, with a little help. She still hurts, rather too much for flexibility.

Castle's plans to visit her are something of a problem. She's already gotten used to sleeping through the night with him, even if she's been too sore to snuggle in. She'll need to waken up, slide out unseen, and be home.

She doesn't want to waken up, slide out and be home. She wants to stay right where she is. She should be snuggled up to Castle as much as possible. Still, if he visits human-Beckett she can provide a little encouragement, as she had planned. So there's a silver lining to that pitch-black thundercloud.

She doesn't wake. Oh, _hell_. She's going to have to make her exit at the riskiest time imaginable: full daylight and morning. Dammit, dammit, _dammit_! She waits till Castle's in the shower – he does love long showers, and she has some thoroughly lustful and lascivious plans for those showers – and sneaks through the main room, listening very carefully. Martha is snoring in a refined fashion. Alexis's schoolbag is missing. Phew. She whips into human, slips out, and whips back to feline. Ouch. That _hurt_. There won't be much of a problem looking pathetic when Castle arrives, because she feels pretty damn pathetic already, just from getting out. Why couldn't he have got a cat-flap that worked _both_ ways? She will have _words_ with him about that. Lots of words, and all of them annoyed.

By the time the cab delivers her to her own apartment, which is a little cold and a lot less caring and welcoming than Castle's loft, she is _almost_ at the point of wishing she'd simply changed back to human-Beckett, told Castle her secret, and stayed. Almost.

She washes, very carefully, regards her appalling bruising with horror, can't face a bra of any sort, and struggles into the softest t-shirt and sweatpants she can find. Even that small concession to civilisation leaves her shattered and sore, and in desperation she lies down on her bed.

She is woken by knocking, which is undoubtedly Castle. She hoists herself painfully to standing and limps to the door. His appalled expression as he takes in her bruises – and that's only her arms, he should see the mess of her torso and thighs, and then kiss them all better – doesn't make her feel any better. He should kiss her now.

He doesn't, though he also recognises her current inability to do anything without wincing. He tidily inserts the lovely bouquet he's brought – _how_ did he manage to achieve such gorgeously scented flowers? – into a vase, puts the chocolate – _oh yes, Castle, you really do observe, don't you?_ He's clearly picked up that addiction – not too far away, and sits next to her. He burbles happily on about their visit to the precinct, which is soothingly mind-numbing since after all she had been _there_ , and then says "both my favourite women getting beaten up". Oh my God. Her jaw drops.

She absolutely does not want him thinking down that line. Not yet. Not now. That is a very bad line for Castle to start on. He's so broad-minded you could run a Mack truck through his head without touching the sides, and he's prepared to believe almost anything – alien abduction, CIA conspiracies, time-travel…. It would be just like him to believe in shapeshifters – in fact, she knows he believes in shapeshifters, and she knows he'd love to be one. Well, only if he could be a large predator. He doesn't want to be a squirrel.

She doesn't want him to be a squirrel either. Human will do fine, for now. And if he's an observant man, with only a very minimal bit of luck he'd be as observant of her likes in bed as he's been observant of Onyx's preferences. Which, in general terms, would be just plain wonderful.

However, while she doesn't want him spotting similarities, she likes being _both_ of his favourite women. She looks at his photos, and pretends not to notice him sneaking closer. After he's made them coffee, in fact, he doesn't bother with the sneaky bit – and she is much amused by his surprise when she lets him cuddle her in, very gently, and warm her up, very nicely. So she tucks her head on to his lovely broad shoulder, by way of reward. For herself.

"Onyx does that," he blurts out. _Oh, shit, so she does. Do not say 'yes I do', Kate_. Dammit. Beckett sits up, which hurts. Castle snuggles her back in, which helps enormously.

"I am not your cat," she snips, absolutely frantically desperate to keep him off that subject. This is getting worse and worse. "Didn't we have that conversation already?"

"I know you're not a cat, Beckett," Castle says. Well, thank God for that. "If you were my cat you'd be curled up in my lap and purring at me, or sprawled over my chest and shoulder. I mean, you could do both of those things and I wouldn't mind a bit, but" –

"Shut up." Shut up, because she wants to do both of those things, very badly, right now – and preferably naked in her bed – and she can remember with pinpoint precision how she'd felt as Onyx (when did she start using his name for herself?) while she was curled in his lap or sprawled on his shoulder because he never stops petting her –

"but you're not a cat." Phew. He hasn't realised anything. It's just his normal flirtation. She can be easy again.

She is easy again. In fact, she's delightfully comfortable. This, Beckett works out, is because Castle is petting her: stroking, feather light, up and down her lividly bruised arms. He's so warm, and broad, and strong, and comforting; and she really, really doesn't want to move. Her eyelids droop, her lashes tumble on to her cheeks, and, as warmly snuggled in the crook of his neck as she has been as Onyx, she drifts silently into sleep.

She's woken by some irritating person tapping at her cheek. _Go away_ , she thinks, as she's happily asleep. They don't go away, and gradually consciousness tells her it's still Castle, and she's fallen asleep all over him. Oooops. She looks at him, his eyes soft and kind and caring and even loving, wonders what to do next, and inadvertently nibbles her lip.

He gathers her in, as gently as he'd carried injured Onyx, and lightly kisses the tip of her nose. She hasn't recovered from that shock when the same butterfly touch lands on her lips.

Oh. Oh oh oh, _oh!_ _Mine. Mine mine mine. Mine._ She stares at him, and then leans forward and kisses his cheek. She'd go full out for his luscious mouth, but he's shifted and she can't reach without hurting herself, which is just _not fair_. It's even more addictive than being petted as Onyx.

"I think," she starts, intending to say _you should do that again and this time let's do it for longer, deeper, better, more_ ; but he interrupts her.

"I think maybe I'd better go home." He looks very nervous and worried.

Go home? No! She doesn't want him to go home. She wants him to stay here and kiss her and cuddle her and care for her. But. Castle can be surprisingly stubborn when he wants to be, and maybe it's best to give him a little time to – er – adjust to a new reality. Okay, she has a plan.

"Yeah… um… if you wanted you could come by tomorrow? Keep me company while I'm not allowed at work?"

He's flatteringly enthusiastic. Good. She's working him round to the right point. Clearly she needs to apply some subtle training techniques, just as she had as Onyx. It's weird, though. She'd have thought that the slightest hint of encouragement would have had him all over her. Well, she'll be round there later, snuggled in as Onyx and almost certainly listening to Castle pour out every last thought and feeling. Then she'll be able to plan her next move with accuracy.

Castle disappears, and Beckett, in default of any better idea, goes back to bed and cuddles her pillow. It's not nearly as nice as cuddling Castle would be. Humph. She falls asleep, though not before setting her alarm to wake her by five, should she not wake naturally. She'll reach Castle's loft by six at the absolute latest, allowing time to change unseen, and then she'll have the whole evening to be petted. That should keep her blissed out for hours.

She wonders if she'll ever tell him that his cat (so he thinks) spent the whole time in a state of complete sexual satisfaction. It's not just the ear-fondling, it's the brushing. Being brushed was totally the best thing ever. It slinked down every single sex-linked synapse and shivered every erogenous zone. Being brushed, she decides, is multiple orgasms for cats.

Her dreams should have turned her pillow, coverlet, bedsheets and indeed bed to ashes. They _scorched_. She has to have another shower before she goes out.

Just as she had hoped, Castle can't resist talking to his cat. (hold on. When did she start thinking of herself as _his_ cat?) It's all perfect. He loved kissing her. He wants to do more of it (so does she). He wants to take another step forward (so does she).

And then he starts to think. This is unwelcome. She really does not want him to think. She just shouldn't have said _if you can find her_ , but she'd been so flustered by the kiss and all her desire for _more_ that she hadn't thought before she spoke. She really hopes Castle's verbosity isn't rubbing off on her. She takes the shortest (and not incidentally the most pleasurable) route to distracting him, by clambering rather painfully on to his shoulder and butting her feline head into his aromatic neck.

* * *

Castle arrives with lunch right on time the next day, much to Beckett's appreciation. They flirt and banter just as they used to, recovering almost all their early mischief, before he – well. Now she sees how he'd misstepped, but it's taken this sneaky way of finding out to discover it. She smiles and snarks and snips at him, and his eyes get darker, and without much ado at all, he slides over with no subtlety at all and kisses her. Very gently. That simply _will not do_. She opens her lips under his and that does it for him. He's careful not to squeeze her, but his mouth is passionate and possessive and raids and oh, that feels so good, _do it some more, Castle; do it some more_.

And then his hand slips down her arm but he catches the bruising, and _ow_! That hurt. She flinches, and _of freaking course because he's a good guy dammit_ he stops kissing her, looks like she slapped him and practically runs out the door. He doesn't even wait till she's untangled her tongue from the kiss to start to tell him not to go.

Dammit!

She gives Castle five minutes – timed – to get out the way, and then skedaddles out of her apartment, into a cab, and off to his block. The excellent Edward lets her in, pushes the lift button for her, and gives her a happy smile. She flicks her tail in thanks and goes up.

Castle is not there. This is not good at all. This is very worrying. She pads around the loft, fretting, and not even able to change to human and have a very strong coffee to calm down. Finally her feline ears pick up the ting of the elevator. She scampers into Castle's bedroom, and plants herself on a pillow, closing her eyes.

Castle's slow, heavy trudge approaches the bedroom. She opens an eye as he flumps miserably on to the bed, and when he doesn't even reach out to her stalks on to his chest and nudges at his chin, to see if Onyx-flavoured affection will cheer him up at all. He wraps big hands over her, and – what? No petting? No movement? Is he ill? Dead? Taken over by aliens? – hang on, that's as insane as Castle. She mews at him, which if she were human would mean _talk to me, tell me what's wrong because you're wrong, love_ – what? Love? Oh God, she is so screwed. Let's leave that for now, Kate, otherwise you'll have a nervous breakdown right here and now. When mews don't work, she butts her head in the way that he always likes and responds to, and when that doesn't work she bats a paw at him. He catches it.

"I'm not really in the mood to play. I think I really screwed up. I shouldn't have kissed her again. She's _injured_ , dammit! But she's just so beautiful and I can't keep away from her and I've been in love with her for months and months and… oh, hell, I've so totally messed this up."

 _He's been in love with her for months_? Well, why the hell didn't he _show_ it? But saying so certainly deserves much encouragement and response. The next time she's human she'll be making sure he's properly rewarded. She pats a paw softly at his cheek: a caress; and nuzzles at him: a feline version of a kiss. This silly, adorable, worried man. He shouldn't worry at all. She can't leave just yet, and she'll need to give it a space in time even when she does, but before the evening is out he will be perfectly reassured and happy again. She purrs at him, trying to indicate that it'll all be okay. Better than okay.

"I don't know what to do. I thought she was enjoying it too but then she flinched and …oh, fuck, what a mess."

 _No, no, no! Absolutely not, Castle. I was enjoying it_. She purrs at him.

"You're simple. I stroke you and you purr." _You stroke me and half the time I come_. "Nothing complicated. People are a lot more difficult. I just wish I knew what Beckett was thinking. I mean, whether she likes me or not. She let me kiss her but then she's injured and I hate the thought that maybe she just let me because she couldn't push me away."

If he's feeling guilty… oh no. She is not having that. They will sort that out damn quick, because like it or not (definitely not) she gets injured on the job. She keeps purring, but bats his face with her paw, leaves it on his cheek, and delicately extrudes her claws. He's being silly, and definitely doesn't need to think that. There is no way on God's green earth that Castle would ever force anything on anyone.

"Don't you start. I don't need you getting upset with me too. What'm I gonna do, Onyx?"

She knows exactly what he's going to do. But first she'll stay here and be comforting for him, snuggle on to him and show him that she's there. After that, she'll go home and solve this issue, and then tomorrow she'll prove it's not just him making moves. Softly, softly, catchee Castle. As a cat, however, she simply purrs and settles down over his heart.

When he finally rises, no happier, she decides that it's time to take action. She sits proudly and demandingly at the door, and though Castle – it's ridiculously protective, but it makes her feel cosseted and cared for – fusses about her going out, and tells her to be back by bedtime (of course she will be), he lets her out.

As soon as she's home, she constructs a text to make it clear that she liked being kissed. Of course, it's Beckett-normal snark, but she can hardly write _I've been sleeping next to you for a week and I love you so get your ass over here so I can prove it_. Though he'd certainly be here at light speed. She taps Send. Castle, on usual performance, will be having dinner and since he'd favoured her with his views on phones at the table (absolutely _never_ , Beckett, how can anyone be so rude! She'd pointed out that she was on call, and he'd accepted that. Grudgingly.) there is a very good chance he won't hear the ting.

Now. Much as she doesn't want to, she'll need to stay here a while. She makes herself some dinner, and then changes to her panther and pads around for a while, uses the scratching post, and makes sure that there are no mice or other vermin. There never are, but she likes to check. If it weren't raining and daylight, she'd go up to the Park for a nice long stretching run, and maybe a bit of squirrel-extermination.

Much, much later, when the rain still hasn't stopped, she reappears at Castle's loft. The doormen have either been briefed by Castle or are remarkably susceptible to mewing cats, because they let her into the elevator and press the button for her.

He's clearly read the text, but possibly only in the last few minutes, because he is blazingly happy. He cuddles and pets her-as-Onyx, but his mind is obviously on Beckett-human. She's really glad she sent it, because his reaction is proof positive that he's telling her cat form the absolute truth. Right. Tomorrow, she'll do something a bit more definite about it.

* * *

 _Thank you to all readers and reviewers, especially guests and those who don't accept PMs._

 _A small reminder: the final chapter will contain some M-rated content._


	5. Chapter 5

_Small reminder that this chapter strays into mild M territory._

* * *

 **Chapter 5: A mystery cat**

Beckett forces herself to do her chores the next day, which is a duty that she dislikes at any time, but especially today. She is having a very hard time controlling her urge to go to the loft, and she's having an even harder time not telling Castle the truth. It's Castle, after all. He believes in _everything_. If she gave him a rainbow unicorn he'd accept it as real and say _Cool!_ , where everyone else would be looking for the surgical stitches and claiming it was a mutilated pony with a cheap dye job.

She has to take this slowly. She has to be absolutely, positively, definitely, incontrovertibly sure that it's real; he's the one; she's the one. Because her whole life will depend on Castle keeping his mouth firmly, totally, shut; on him never revealing anything to a single soul.

Because if he ever did, she'd have to leave. Change her whole identity. She'd never be able to be a cop again, because one run through the databases and she'd be known. A real shapeshifter? She'd be a media show; a story for every quiet news day. And worse, she'd be studied. Examined and investigated; poked and prodded and DNA tested and made to change till they discovered how. Magic doesn't cut it as an answer when the scientists get interested. Scalpels, however, would.

He hasn't suspected anything yet, thank heavens. It doesn't seem to have crossed his mind. So it's okay. She can go over this afternoon – yes, this _afternoon_ , not _now_ – and take a DVD, and snuggle up, and kiss him. That'll show him she's into this. She'll take Forbidden Planet, since he'd said he loves it, and if he's seen it lots, it won't matter if he's not paying attention. She hopes he won't be paying attention to the film.

She grumbles and mutters and does her chores and resolutely does not call, text or visit Castle until after lunchtime, of which she manages to partake, with astonishing self-discipline, at the normal time, rather than eleven a.m. Some of her frustration is no doubt because last night's petting didn't include quite enough ear-fondling to be wholly satisfying, and as a cat she can't tell him what really, really makes her happy. Now that she knows what Castle's hands can do for her, her own fingers and toys are not nearly as good.

She congratulates herself on her self-discipline all the way to Castle's loft. Then she congratulates herself some more for not simply jumping him as soon as she enters, though that has more to do with her still-sore bruising and creaking than anything else. She is presented with coffee, curls up in a corner of the couch, and listens to Castle complaining about the lack of cat to meet her. She replies with a considerable number of putting-him-off-the scent comments, which seem to work. Though there is a nasty hitch when he enquires about her health, and then stops dead after saying _Same as Onyx_. However, he starts the movie and his lips are moving along with the lines, so he can't have jumped to any conclusions. Phew.

Far more usefully and pleasurably, she hasn't even had to move before he's draped an arm around her. She responds by cuddling in, then drops her head on his shoulder and puts a hand on his knee. That should give him a clue or three. Happily, he takes them. His arm slides down and around so that his hand is on her hip, and she wiggles to be entirely tucked in and cosily warm. Ohhhh, this is just perfect. Now, will she need to make another move –

No. Because Castle has tipped up her chin – oh, ooops, she's purred even before he's kissed her. That's not a proper kiss, though – and she opens under him, licks along his lips and demands entry, to which he accedes instantly. She stoops, swoops and conquers: taking his mouth as if she'd always had the right; and _oh_ , he's so _good_ at this, letting her raid and then ravaging himself; she's heating up faster than oil on a griddle but she can't do anything that might make her wince, because he'll stop, and she'll have to stop, and she doesn't want to stop. Her hand has sneaked on to his shoulder, and she'd love to be on his lap and then all sorts of clothes-opening would be possible, but he's being cautious with his hands (humph!) and she's not going to risk this being messed up again like it was yesterday.

She keeps kissing him, showing with every sweep of tongue and nip on his lips that she wants this, and him, until he pulls off and stares at her with midnight eyes and sheer desire. His words fall out of his mouth with no input from his brain at all, and she smiles inscrutably and teases him with more words. He responds in kind, claiming that she's mean. Well, yes, of course, but not malicious. But – _if she was a cat she'd be playing with her prey_? That's far too near the knuckle. She feels the urge to change to her panther, and show him exactly how a big cat plays with its (sexual) prey, and only just resists.

Instead, she makes sure he knows he's invited over tomorrow, and sinks into his farewell kiss for far longer than she'd intended. She could spend a lifetime in his arms, in his kiss, tucked against his broad bulk; safe, cosseted, cared-for and loved. She manages – just – to bid him goodbye, and to go home.

She counts every second of every minute until she can leave again: telling herself it's ridiculously teenage, that a mature woman – or feline – does not let herself be totally enraptured by anyone. She entirely fails to convince herself, and, as Onyx, is back with Castle by dinner time, feeling delightfully happy, content and ready to be petted as extensively as normal.

Besides which, he's sure to tell her how he felt about the progress of their relationship, and then she'll be able to plan the next step of her careful seduction.

It all starts to go shatteringly wrong after dinner. Castle _thought she might be Beckett in disguise_? What the actual _fuck_. He can't think that. Even Castle isn't that insane. And by the way, Castle, it is _not_ flattering that her lovely Onyx-form is not as fitting as a panther, tiger or leopard – though she's the first of those too. She regards him with annoyed dislike, and he admits that it's nonsense, and he's being silly. Good. Hold that thought, Castle, for a _long_ time. He invites her up, and she curls against him to be stroked. That's better. Lots of lovely firm stroking. She could stand a considerable time of firm stroking, and not just as a cat. She thinks about firm strokes and purrs happily. He expresses concern about Beckett-human, and she miaows and curls in even more, so that he plays with her ears in that wholly erotic way that simply does it for her, and it does.

And it would have done again, if he hadn't gone back exactly where he shouldn't. Looking up shapeshifter detection devices and methods? Ugh, ugh, ugh. She glares at him viciously. He won't be feeding her any of those. No way. And while he's researching, he's not focused on her, which is also not acceptable.

However, he hasn't found anything useful. Good. Castle might be pouting, but she's relieved. She snuggles over his chest and accepts his petting as only her due, sinking into a contented haze of sensuality which lasts all evening. He seems to have given up searching for something he won't find.

In the deep of the night she slips away, ever more regretful. The cab drops her at her door, and she changes and sneaks in, invisible in the dark. She always sneaks up late at nights as a cat. It prevents anyone noticing her, and it's only one floor. The stairwell door is easy to push open, and she prowls out –

 _Oh, shit!_ Her nose picks up the scent of Castle's aftershave almost as soon as she's out of the stairwell. How the _hell_ did he get here? _Why_ did he come here? He couldn't have spotted her leaving – could he? He's slept like the dead every other night, why should he wake tonight? She tries to retreat before she's spotted, but Castle moves far faster than she'd ever thought he might be able to and catches her.

"What are you doing here?" he asks. She really doesn't like that gently enquiring tone. It's far too close to her own, as used in Interrogation. She doesn't like the note of _I want answers_ , either. This sounds far too much like Castle having reached some entirely correct conclusions. Why does he have to have a mind as broad as Montana? Nobody else would even have _thought_ that she might be a shapeshifter, still less _investigated_ it. "More to the point, how did you get out? Last I knew, cats couldn't manage door handles. Not mine, anyway."

He picks her up. This is not an improvement. "I thought it was all a coincidence, but it wasn't, was it – Beckett." Oh, _hell_. He really has worked it all out. Damn, _damn_. She spits and hisses angrily. "You wouldn't know how to come here unless you lived here, and if Beckett had had a cat – you – she'd have taken you back as soon as I showed her the photos." Beckett loses her feline cool, and takes a hopeless, infuriated swipe at him. All that gets her is Castle taking a firm hold of her front paws. "How'd you do it?"

She makes frantic efforts to escape him, twisting and wrenching, hurting still-unhealed bruising, manages to elude his grip and leap away, but when she hits the floor it's _agonising_ and she can't quite get through it to run before he's trapped her again, folding her in to stop her kicking and scratching, calm strength proof against her desperate efforts to get away, to protect her secret, to hide. Eventually, tired and in pain, she stops, and simply fixes him with an evil glare, ears flat, tail lashing, more furious with herself than him.

If only she'd been more careful. If only she'd taken a sniff of the air before she opened the stairwell door. Now it's all ruined.

"Stop running away, _whoever_ you are," he says, but it's all too horribly clear that he's dead certain she's Beckett. Especially once he notices the cat-flap. Why'd he have to be so damn smart? She droops, utterly unhappy.

"C'mon. I've worked it out now. You might as well admit it. Besides, this is so _cool_. I can't believe you really exist. It's amazing. Fabulous. Fantastic."

Freaking typical. Only Castle could be that enthusiastic and instantly believing. His fingers are already starting to pet and stroke.

"If I let go, will you open the door?" he asks, all his tones hopefully persuasive. "I think we've got a lot to talk about." He strokes her gently, which is absolutely _not fair_ because she's already melting under his touch, sensations wriggling along her spine, and it is totally unreasonable that she just wants him to keep petting _ohhhh_ just like that. She shouldn't be seduced into concessions. "A _lot_ to talk about," he pleads.

She looks at him, no longer fighting, trying to understand if she can trust him. It's too late if she can't, she realises. She has one chance – and she can either blow it now, or believe in him.

She climbs on to his shoulder, butting her head into his neck, and hopes like hell she's got this right. His clever, caring hands stroke her, and she gives in. She purrs. "Okay then, deal," he agrees, and lets go to allow her to slither through the door.

She changes to Beckett, and opens up.

Castle simply gathers her in, as close as he can, leans his forehead on hers: the same sincere caring that he'd only shown to Onyx: holds her yet, truth in every second; until at last he runs slow, gentle strokes up and down her spine, just as he would do for Onyx, somehow knowing that in either form she's pettable.

"I've got you. Whoever you are, I've got you and I am _keeping_ you," he says, confident that she'll not deny him. He tips her chin up, just as he had earlier, and kisses her with the same passion and power: taking and giving and demanding and receiving. She slides hands round his neck and pulls him down and back to her lips: opening for him and arching against his width, sensing the swelling firmness pressing into her with delight; squirming closer and never stopping kissing him.

When they stop, she'll have to talk. She kisses him further, delaying as long as possible, but eventually he lifts away, which is unwelcome, sits them down with her in his rather over-excited lap, which is better, and asks her not _why_ , but _how_?

Well, she's not telling him the whole history. Besides which, though she does now know _how_ , a girl – or cat – has to keep some secrets. The man is practically bouncing with delight. Honestly, what a _child_. Anyone would think all his Christmases had come at once. Just because he's found out that shapeshifters – one shapeshifter, she's never found another one, which is why she's currently in this position– exist, he's behaving like he's had a new toy. He wants a demonstration, and whines _pathetically_ until she gives in, and then he's even bouncier. It's like having a human trampoline, there's so much bounce.

Of course, this is Castle. Of course he's interested in the clothes. Or lack of clothes, more like. There is some very sensual mischief dancing in his eyes, and she's quite sure he knows perfectly well that his fingers are still stroking, cat or woman.

And then he works out something she'd really rather he hadn't.

"You _spied_ on me," he growls. Well, yes, but _spied_ is such a nasty way to put it. He didn't have to take the cat home. "You cheated." Not at all. All's fair in love and war, Castle. Doesn't he know that? He's promising her wicked things, though, as she flirts with him, and she's reacting to that, and the fidgeting fingers. Unfortunately he's not quite distracted enough. Yet. In true Castle fashion, he just keeps pushing – and then he works out exactly why she'd originally padded down the alleyway and she's sure her blush could start forest fires upstate in winter.

"I like petting you," he says in a velvet tone that strokes her nerves all the way down. "Cat or not." And he begins. The first stroke is slow, smooth and sensuous, from head all the way down to where her tail would be. She curves into it, and he glides around her hip to land on her thigh: close but not quite close enough. She's already aroused before his warm palm meets the soft skin of her waist: the first time he's touched there in human form. His light touch _scorches_.

He leans in slowly, intent in every lineament, and she falls into his mouth without a single hesitation. The fingers that were so incredibly good at petting a cat turn out to be as arousing when she's human: sliding up under her t-shirt to skate over her back and press her in, easing a fraction as she opens his shirt and then, her tee discarded over her head, she turns against his skin and surrenders to every erotic, arousing sensation. His hands skim over her, learning as they go; his mouth doesn't move from hers as he lays her a little back and palms her breasts: as good as fondling her feline ears, bringing a moan from her lips and a purr following it as he plays and pets. She's soaked and he's still playing with her, but her hands are wreaking some erotic havoc of their own.

He stops kissing her, which he shouldn't do: she scratches very lightly and emits a small, disappointed noise, but when his mouth slips behind her ear she opens her throat to him as any feline might do and pulls his head down. She's already so close, and then he nibbles downward and starts to play again and it's all flowing south: he teases her and tantalises, plays with the soft skin – she's still too sore to wear a bra and he's loving that – a tiny, gentle nip, a suck, and she's gone on a long, soft sigh.

"Take me to bed," she purrs seductively. "After all, I've spent plenty of time in yours."

"Come here, then. You don't need to be a cat for me to carry you to bed." He sweeps her up, stronger than she'd expected, and kicks her bedroom door shut behind them, stands her up and presses her in, hard against her; slides off her sweatpants as she's pushing away his button-down; resisting just a fraction as her wicked hands move to the front of his pants and explore.

"Naughty, naughty," he smiles. "So impatient."

"Turnabout is fair play," she husks, and flicks his pants open, long, delicate fingers slipping inside to explore and tease; circle and slide. Castle groans, and takes her mouth with an aggressive kiss that lights them both up. His pants hit the floor. Beckett hits the bed, Castle over her, pulling him down to her so she can arch and rub against him, he's ripping her panties away and discarding his boxers and there's no more play, no teasing, no need because she's soaked and he's rock-hard and then he's finally, finally within her where he ought to be and there's no more thinking, just the man and the moment.

Castle slips off her, and pulls her across him so that she's tucked over his chest and he can stroke her hair and down her back, which he does, just as he would if she were Onyx. She nestles in.

"That's better," he rumbles. "I like you just as much this way." His petting strokes up and down her spine. She flexes against it, and murmurs contentedly, and then curves her hand around his stubbled jaw. His smooth stroking reaches a little further down each time, gliding over the taut swell of her ass. She shifts position a fraction, curling one leg around him in opened invitation. His clever fingers take slow advantage, slicking through her, easy, unhurried touches. She turns her head against his pecs and lets her tongue stray, twine around his nipple. There's no rush. Slow can be very, very satisfying.

He begins to rise and fill against her again, as she is becoming hot and wet under the delicate, drugging movement of broad, long digits and the flex of his thighs widening her for him. She moves sensuously against him, as flexibly as the cat she is, and he makes a low noise deep in his throat before she kisses him into silence and slides against him to take him in once more. He fits perfectly: hard and long, deep within her; and for a moment they're both still, joined as close as they can be and learning each other's intimate spaces.

"You feel so good," he murmurs, and she wriggles just a tiny amount and hums, because he feels just as good but she doesn't want him to stop kissing her because that makes it feel even better. She moves slowly, and he slides her back equally slowly, large hands spanning slim waist; until slow slides merge imperceptibly into harder thrust and then there's only her and him and them and bliss.

"Will you still be Beckett in the morning?" he asks her, stroking gently over her side.

"Whoever you like," she says, and tucks her head into his neck and her arm across him, so that her head is just where Onyx would have been.

"I like you both," Castle says, utterly satisfied. "It's just so _cool_ that you're my cat."

 _ **Fin.**_

* * *

 _Thank you to everyone who's come along with the Cats' adventure, and especially those who have reviewed, guest and named._

 _I'm not sure when the next instalment of the Cats will be, since I'm still writing it and it will be more than a two-shot. Also in progress is a serious story. I am not abandoning this fandom._


End file.
